The present invention relates to an air-bag arrangement, and more particularly relates to an air-bag arrangement mounted in a motor vehicle.
When a motor vehicle is involved in an impact, especially a front impact, the floor pan of the vehicle may be distorted. The distortion of the floor pan may be such that, if no protection is provided, a very substantial upward acceleration is applied to the feet of an occupant of the vehicle. This acceleration, although being an acceleration of a very short distance, may lead to substantial injuries to the feet or ankles of the occupant of the vehicle.
It has been proposed to provide an air-bag or inflatable element located on the floor of the foot-well of a motor vehicle at a position beneath the feet of the occupant, the air-bag being adapted to be inflated as a consequence of an impact being detected, the inflated air-bag thus serving to lift the feet of the occupant above the floor pan of the vehicle, providing a desirable degree of protection.
Various difficulties have to be overcome in designing an air-bag for use in the foot-well of a motor vehicle, to lift the feet of the vehicle occupant. The air-bag should be mounted in position to cover, in the uninflated state, an area of the metal floor pan of the vehicle in the foot-well. Whilst the metal floor in the foot-well can, in some vehicles, be covered by a soundproofing material, which may be soft or resilient, in many motor vehicles no such soundproofing material is provided, and the floor pan of the vehicle thus presents a generally abrasive surface. If a conventional ail-bag is provided which is simply placed on the metal floor of the floor pan, in an uninflated state, with means being provided to inflate the air-bag at an appropriate moment, there is a risk that the air-bag will be damaged since the air-bag will, every time that the vehicle is used, be pressed between the carpet and the floor pan by the feet of the person ordinarily occupying the vehicle. Even if the air-bag is initially stored within a casing or housing, there is a risk that the air-bag will be punctured on inflation of the air-bag if parts of the air-bag come into contact with the floor of the vehicle.
It is to be appreciated that in many cases the space adjacent the floor of the vehicle within the foot-well of the vehicle, that is to say the space beneath the carpet and immediately above the floor pan, may become damp. If a conventional air-bag material is utilized in such an environment, there is a risk that the fabric may become mildewed and perish.
It is also to be appreciated that in a typical motor vehicle the floor or lower surface of the foot-well may be uneven or xe2x80x9cstructuredxe2x80x9d. Thus the floor or lower surface of the foot-well may be provided with integral strengthening ribs or undulations. This can cause problems with the fitting of a conventional air-bag intended to lift the feet of the occupant of die vehicle, and may also lead to problems related to the distribution of a load passed through an air-bag provided to lift the feet of the occupant of the vehicle.
If a conventional air-bag is utilized at a position between the floor pan and the carpet of a motor vehicle, if the feet of the occupant are pressed firmly downwardly at the moment that the air-bag is inflated, initially the parts of the air-bag which are not subjected to the downward pressure from the feet will be inflated, and only as a final stage in the inflation of the air-bag will the part of the air-bag located immediately beneath the feet of the occupant be inflated so that the feet are actually lifted up above the floor pan. This is undesirable, since ideally the feet of the occupant should be lifted above the floor pan just as soon as possible when an impact of the vehicle is detected.
The present invention seeks to provide an improved air-bag arrangement.
According to one aspect of this invention there is provided an air-bag unit adapted to be positioned on the floor pan of a motor vehicle in the foot-well to be located beneath the feet of an occupant of the vehicle, the air-bag unit having a substantially sealed damp-proof housing containing an air-bag, the housing having a substantially rigid upper cover, the unit being such that on inflation of the air-bag the cover of the housing is lifted, from its initial position to an elevated position, wherein the cover of the housing is secured to the base of the housing, the cover being adapted to be separated from the base of the housing on inflation of the air-bag.
Preferably the cover is sonic-welded to the base of the housing.
According to another aspect of this invention there is provided an air-bag unit adapted to be positioned on the floor pan of a motor vehicle in the foot-well to be located beneath the feet of an occupant of the vehicle, the air-bag unit having a substantially sealed damp-proof housing containing an air-bag, the housing having a substantially rigid upper cover, the unit being such that on inflation of the air-bag the cover of the housing is lifted, from its initial position to an elevated position, wherein the cover is secured to a base part of the housing by means of a deformable side wall.
The side wall may be a concertina-style side wall.
It is to be appreciated that a sealed damp-proof housing will minimize the risk of a fabric air-bag deteriorating even if the air-bag is in a potentially damp environment.
Preferably the housing is provided with mounting means to mount the unit in position.
Conveniently the air-bag comprises two super-imposed layers of fabric, the layers being secured together to define a plurality of discrete cells.
Advantageously the cells comprise a plurality, of substantially parallel cells which are substantially cylindrical when inflated.
In an alternative embodiment the cells comprise a plurality of cells configured so that on inflation of the cells one end of each cell has a greater diameter than the other end of the cell. Thus the cells may be substantially triangular.
Preferably the air-bag is provided with a gas supply tube adapted to be connected to a gas generator.
The unit may be provided in combination with a gas generator connected to the gas supply tube, the gas generator being associated with a sensor adapted to respond to an impact.
In an alternative embodiment of the invention a gas generator is provided within the housing to provide gas to inflate the air-bag.
Conveniently electrical connection means are provided to enable means supplying a signal adapted to initiate inflation of the air-bag to be connected to the gas generator. Preferably the unit has a substantially rigid base.
In one embodiment of the invention the base has a deformable peripheral region, a terminal lip of the peripheral region being secured to the cover.